"He's been important for both United and England since he was a teenager because of the threat he offers to any team he's in.
"He's got a lot of different qualities, and we know he can be dangerous at the weekend."
Reigning champions City are second in the standings, six points ahead of neighbours United in eighth.
City crushed United 6-3 at the Etihad Stadium last season but lost the away game 2-1. They also beat Erik ten Hag's side in the FA Cup final in June and later matched United's 1999 achievement of the treble.
But Walker is now looking at the bigger picture.
"Last season is done, we lost at Old Trafford and went on to win the treble. Ultimately that's what matters," the 33-year-old Walker added.
"We want to win the game because of what it means and because, ultimately, it will help us in trying to win the Premier League again. We don't need to think beyond that.
"We've had some great games against them in recent years and our focus is on giving the fans something to enjoy again on Sunday."
Published 29 October 2023, 00:51 IST